JP2008-291852A discloses a first variable valve timing mechanism for changing a lift amount of an intake valve and a second valve timing mechanism for changing a center angle of a lift of the intake valve as variable valve timing mechanisms for changing a valve timing of an internal combustion engine. These two variable valve timing mechanisms correct one position according to another position when the internal combustion engine is started.
JP2011-179418A discloses a variable valve timing mechanism configured to change a valve timing of an internal combustion engine using a hydraulic pressure and including a locking mechanism for locking the valve timing in an intermediate timing.